1. Field of the Invention
The present invention relates to an engine unit.
2. Description of the Related Art
An engine unit includes an oil tank configured to store lubricating oil of an engine. For example, the oil tank is disposed forward of the engine in a structure described in Japan Laid-open Patent Application Publication No. JP-A-H09-317431. The oil tank includes upper and lower portions that are provided as discrete elements and are joined to each other.
When fabricating an oil tank by die casting, the oil tank is required to have a draft angle on its inner surface so as to facilitate its removal from a die. Therefore, when the oil tank is structured to be split into the upper and lower portions as described above, the thickness of the upper portion of the oil tank increases upwardly. On the other hand, the thickness of the lower portion of the oil tank increases downwardly. Put differently, the thickness of the oil tank increases with the distance from a joint surface between the upper and lower portions. Especially when the oil tank has a shape elongated in the up-and-down direction, the thickness of the oil tank further increases. This results in the drawback of reducing the capacity of an oil storage space inside the oil tank.